1. Field of the Invention
This invention relates to a means and method for nondestructive evaluation of flaws in a host material by utilizing the data derived from ultrasonic transducers, and in particular, relates to flaw reconstruction utilizing an ultrasonic multiviewing transducer data acquisition system in the long and intermediate wave lengths.
2. Problems in the Art
Knowledge of flaws and related properties of materials is of extraordinary value. Accurate information of that kind, especially with regard to materials which are used in high stress or safety sensitive applications, provides maintenance and inspection personnel with the ability to reject, repair, or replace the materials or parts which are subject to failure, thereby averting damage or even loss of life.
One method of attempting to obtain flaw information involves taking portions of the material and breaking it down to analyze its properties and to identify characteristic flaws. The obvious shortcoming of this method is that it does not allow evaluation of materials in existing use (it is destructive as compared with non-destructive), and only would give an estimate of material properties for prediction of possible later forming flaws.
Therefore, methods of flaw evaluation were developed which allow unlimited and possibly even in-use analysis of materials (non-destructive evaluation). Non-destructive evaluation (NDE) does not require "destruction" or alteration of the part or material in order to derive information concerning flaws therein. Currently, there are many different forms and methods of NDE including, but not limited to, such different procedures as ultrasonic waves, electromagnetic eddy currents, thermal wave imaging, nuclear magnetic resonance (NMR), and x-ray technologies.
An illustrative example of the advantages of NDE is as follows. Turbine fan blades for jet aircraft engines are under tremendous forces and stresses during operation, and are critical to the continuing operation of the engine. Because of the critical nature of these parts, and the knowledge that a very small percentage fail due to inherent flaws after a certain period of time, all of these parts are replaced and discarded after the minimum period of time. Unfortunately, most of the other blades would have useful lives of up to ten times the life span which they are actually used. NDE now allows the parts to be screened so that the small percentage which probably would fail can be detected during routine maintenance and discarded, whereas those parts not exhibiting the flaw characteristics could continue to be used, saving tremendous amounts of money. It has been estimated that for one particular type of jet engine alone currently being used, annual savings would run into the tens of millions of dollars.
While NDE is very promising from the standpoints of economy and safety, no NDE system has yet been developed which can consistently, accurately, and efficiently analyze and identify flaws of all types and shapes to the extent necessary to achieve the desired accuracy demanded by industry and the military. There is a real need for an NDE system which accurately can derive size, shape, location, and orientation of flaws.
Electromagnetic eddy current NDE systems are restricted to near surface flaws in materials. Thermal wave imaging NDE systems cause heating of the material being tested. NDE and x-ray technologies are very high in cost and are not generally cost-effective for broad applications.
Current ultrasound technology utilizes various methods itself. All are based on interrogating the material being studied by introducing ultrasonic waves into the material and then analyzing the reflected waves coming back to derive the desired flaw data. Some systems utilize one transducer which sends and receives ultrasound energy whereas other systems utilize multiple transducers. In fact, one method utilizes hundreds of transducers in an effort to attempt to construct a three dimensional image of the flaws.
The present ultrasonic NDE methods are deficient in that they either are not able to accurately identify and reconstruct the flaws, are unable to derive the required information to be beneficial, or utilize such complex structure to make it uneconomical or impractical.
Therefore a real need exists for an NDE method and means for reconstruction of flaws which accurately identifies and reconstructs the size, shape, and orientation of flaws in the material, while additionally avoiding the requirement of physically scanning the flaw and using much higher frequencies which exhibit increased problems with attenuation.
It is therefore a primary object of the invention to improve over and solve the problems and deficiencies in the art.
A further object of the invention is to provide a means and method for reconstruction of flaws in materials which accurately identifies and reconstructs the size, shape, and orientation of the flaws.
A further object of the invention is to provide a means and method for acquiring flaw data which takes into account and corrects attenuation, diffraction and interface losses of the material, and any problems involved herewith.
Another object of the invention is to provide a means and method for flaw reconstruction which allows for multiple viewing options for the ultrasonic transducers according to desire.
Another object of the invention is to provide a means and method for flaw reconstruction which can utilize long and intermediate wave lengths of ultrasound to accomplish the same.
A further object of the invention is to provide a means and method of flaw reconstruction which allows for automatic and remote control of the adjustment of the ultrasound transducers so that their time paths are equalized and this equalization can be maintained.
A further object of this invention is to provide a means and method for flaw reconstruction which utilizes a plurality of transducers.
Another object of the invention is to provide a means and method for flaw reconstruction which can produce a three dimensional model of the flaws in the materials and can provide documentation and visualization of the same.
A further object of the invention is to provide a means and method of reconstruction of flaws which combines the system of deriving flaw data utilizing ultrasound, with computer means and software programming means to automatically control the positioning and adjustment of the transducers and to mathematically operate upon the derived flaw data from the transducers to identify and reconstruct flaws in the material.
Further objects, features, and advantages of the invention will become apparent with reference to the accompanying specification and drawings.